Light pen, photo detective liquid crystal display device and display device having the light pen

ABSTRACT

A photo detective LCD device includes a light pen. The light pen includes a body, a driving pulse generating module and a light generating module. The body has a pen shape, and an end of the body includes an opening through which light exits. The driving pulse generating module is disposed in the body and generates first and second driving power pulses having first and second frequencies, respectively. The light generating module generates first and second light in response to the first and second driving power pulses, respectively. The first and second light flickers in a third frequency and a fourth frequency, respectively. The power consumption is reduced, and the brightness of sensing light is enhanced. The light pen generates light having at least two different frequencies, and the display device recognizes light generated from the light pen effectively. Therefore, the display device may operate without failure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.2003-19603 filed on Mar. 28, 2003, Korean Patent Application No.2003-24382 filed on Apr. 17, 2003, and Korean Patent Application No.2003-39340 filed on Jun. 18, 2003 under 35 U.S.C. §119, and U.S. patentapplication Ser. No. 10/805,961 filed on Mar. 22, 2004 under 35 U.S.C.§121, the contents of which in their entirety are herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light pen, a photo detective liquidcrystal display device, and a display device having the light pen

2. Description of the Related Art

Display devices may be divided into a cathode ray tube (CRT) typedisplay device, an electroluminescent display device (ELD) and a liquidcrystal display (LCD) device.

A first type display device receives video signals from aninformation-processing device and converts the video signals so as todisplay an image. The first type display device communicates with theinformation-processing device in a one-way fashion. A user inputs datainto the information-processing device by means of input devices such askeyboard, keypad and mouse, etc.

A second type display device receives first video signals from aninformation processing device, converts the first video signals so as todisplay an image, and also outputs signals inputted onto the screen ofthe display device by the user to the information processing device. Inother words, the second type display device communicates with theinformation-processing device in a two-way fashion.

The second type display device further includes a touch panel so as toperform the two-way communication. The touch panel detects the pressuregenerated by a hand of the user or a touch pen, and outputs positiondata to the information-processing device. The position data designatesthe position of the point to which the pressure are applied. A selectedposition is perceived via the touch panel. The information-processingdevice receives the position data, generates second video signals usingthe position data, and outputs second video signals to the second typedisplay device.

However, the second type display device has an increased thickness andweight due to the touch panel so as to communicate with theinformation-processing device in the two-way fashion. The second typedisplay device using the touch panel may not display minute images andcharacters.

A third type display device senses the light inputted from the user,communicates with the information processing device in the two-wayfashion, and outputs minute images and characters to the informationprocessing device. The third type display device has a plurality ofphoto sensors. The photo sensors have a minute size and are arranged ina matrix shape. The display device transforms the light detected by thephoto sensors into a signal so that the information-processing device isable to perceive the signal corresponding to the light detected by thephoto sensors, and outputs the signal to the information-processingdevice. The information-processing device outputs a new video signal tothe display device in response to the signal received from the displaydevice. The display device displays a new image in response to the newvideo signal.

The user applies the light to the photo sensors of the display device bymeans of a light pen. The conventional light pen generates the lightonly when the light pen applies more than a predetermined pressure tothe surface of the display device so as to reduce power consumption ofthe light pen.

The conventional light pen consumes little power. However, the usershould always apply more than a predetermined pressure to the surface ofthe display device by means of the conventional light pen. Therefore,the user may feel fatigued when the user presses the surface of thedisplay device by means of the conventional light pen for a long time.In addition, the display device may be scratched and damaged by thelight pen. In addition, the conventional light pen has lens and have acomplicated configuration. Therefore, the cost for manufacturing thelight pen may increase, and the weight and volume of the light pen mayincrease. Further, the photo sensors may mistake an external light forthe light generated from the light pen, so that the display device mayoperate in the wrong way.

SUMMARY OF THE INVENTION

Accordingly, the present invention is provided for substantially obviateone or more problems due to limitations and disadvantages of the relatedart.

It is a first feature of the present invention to provide a light penhaving a simple structure and a reduced weight. The light pen may bemanufactured by a reduced cost. The light pen need not apply anypressure to the surface of the display device, and generates light whenthe light pen touches the surface of the display device. Therefore, thedisplay device may operate without failure.

It is a second feature of the present invention to provide a photodetective liquid crystal display device having the light pen.

It is a third feature of the present invention to provide a photodetective display device having the light pen.

In at least one exemplary embodiment, a light pen includes a body, aphoto detective module, a control module and a light generating module.The photo detective module is disposed in the body and detects a firstlight inputted from an external source to output a sensing signal. Thecontrol module outputs a control signal in response to the sensingsignal. The light generating module receives a driving power signal inresponse to the control signal to generate a second light.

In at least one other exemplary embodiment, a light pen includes a body,a driving pulse generating module and a light generating module. Thedriving pulse generating module is disposed in the body, and generates afirst driving power pulse having a first frequency during a first timeperiod and a second driving power pulse having a second frequency duringa second time period. The light generating module generates a firstlight in response to the first driving power pulse and a second light inresponse to the second driving power pulse, the first light flickers ina third frequency, and the second light flickers in a fourth frequency.

In another exemplary embodiment, a light pen includes a body having afirst end and a second end and a light guiding unit. The light guidingunit is coupled to the second end of the body, and guides a first lightgenerated from an external source toward the first end of the body.

In still another exemplary embodiment, a liquid crystal display deviceincludes one of above mentioned light pens, a liquid crystal displaypanel and a driving module. The liquid crystal display panel includes afirst substrate, a second substrate facing the first substrate, a liquidcrystal layer interposed between the first substrate and the secondsubstrate, a plurality of first electrodes disposed on the firstsubstrate, a second electrode disposed on the second substrate, and aphoto detective element. The photo detective element is disposed betweenthe first electrodes, and detects the second light to output a secondsensing signal having a position information. The position informationhas a position to which the second light is incident. The driving modulegenerates first and second driving signals. The first driving signal isapplied to the first and second electrodes so that the liquid crystaldisplay panel outputs the first light, and the second driving signal isapplied to the first and second electrodes in response to the secondsensing signal so that the liquid crystal display panel outputs a thirdlight.

In still another exemplary embodiment, a liquid crystal display deviceincludes one of above mentioned light pens, a liquid crystal displaypanel, a sensed signal processing unit and a driving module. The liquidcrystal display panel includes a plurality of pixels and a photodetective element. The pixels control a transmissivity of a third lightpassing through a liquid crystal layer to display an image. The photodetective element is disposed between the pixels, and detects a positioninto which the first and second lights are incident. The sensed signalprocessing unit includes a comparator module, and the comparator modulecompares a first intensity of a first sensing signal with a secondintensity of a second sensing signal. The first sensing signalcorresponds to a third light inputted from an external source, and thesecond sensing signal corresponds to the first and second lights. Thedriving module generates first and second driving signals, the firstdriving signal is applied to the pixels, and the second driving signalis applied to the pixels in response to the second sensing signal.

In still another exemplary embodiment, a liquid crystal display deviceincludes a first substrate, a second substrate and a liquid crystallayer disposed between the first and second substrates. The firstsubstrate includes a first transparent substrate, a pixel voltagesupplying part, a detective element, a color filter disposed in thepixel region, and a pixel electrode. The detective element is disposedin a second portion of the pixel region, detects an external signal tooutput a position signal, and the position signal has a position towhich the external signal is applied. The color filter is disposed inthe pixel region, and the pixel electrode is disposed on the colorfilter to receive the pixel voltage. The first transparent substrate hasa pixel region, and the pixel voltage supplying part is disposed in afirst portion of the pixel region, and outputs a pixel voltage. Thesecond substrate includes a second transparent substrate facing thefirst transparent substrate, and a common electrode disposed on thesecond transparent substrate to face the pixel electrode.

In still another exemplary embodiment, a display device includes one ofabove mentioned light pens, a display unit and a driving module. Thedisplay unit includes a plurality of photo detective elements. The photodetective elements outputs the first light, detects the second light tooutput a second sensing signal having position information. The positioninformation has a position to which the second light is incident. Thedriving module generates first and second driving signals. The firstdriving signal allows the display unit to output the first light, andthe second driving signal allows the display unit to output a thirdlight in response to the second sensing signal.

In still another exemplary embodiment, the display device includes oneof above mentioned light pens, a display unit, a sensed signalprocessing unit and a driving module. The display unit includes aplurality of photo detective elements for detecting a position intowhich the first and second lights are incident. The sensed signalprocessing unit includes a comparator module, and the comparator modulecompares a first intensity of a first sensing signal with a secondintensity of a second sensing signal. The first sensing signalcorresponds to a third light inputted from an external source, and thesecond sensing signal corresponds to the first and second lights. Thedriving module generates first and second driving signals, the firstdriving signal allows the display unit to output a fourth light, and thesecond driving signal allows the display unit to output a fifth light inresponse to the second sensing signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantage points of the presentinvention will become more apparent by describing in detailed exemplaryembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic view showing a light pen according to a firstexemplary embodiment of the present invention;

FIG. 2 is a schematic view showing a light pen according to a secondexemplary embodiment of the present invention;

FIG. 3 is a graph showing driving power pulses generated from a lightemitting module of the light pen of FIG. 2;

FIG. 4 is a schematic view showing a light pen according to a thirdexemplary embodiment of the present invention;

FIG. 5 is a partially enlarged view showing ‘A’ of FIG. 4;

FIG. 6 is a schematic view showing a light pen according to a fourthexemplary embodiment of the present invention;

FIG. 7 is a schematic view showing a light pen according to a fifthexemplary embodiment of the present invention;

FIG. 8 is a schematic view showing a light pen according to a sixthexemplary embodiment of the present invention;

FIG. 9 is a graph showing first and second driving power pulsesgenerated from a driving pulse generating module of FIG. 8;

FIG. 10 is a graph showing brightness measured at the light emittingmodule in response to the driving power pulses of FIG. 9;

FIG. 11 is a graph showing first and second driving power pulsesgenerated from a driving pulse generating module according to a seventhexemplary embodiment of the present invention;

FIG. 12 is a graph showing brightness measured at the light emittingmodule in response to the driving power pulses of FIG. 11;

FIG. 13 is a partial cross-sectional perspective view showing a lightpen according to an eighth exemplary embodiment of the presentinvention;

FIG. 14 is a schematic view showing a photo detective liquid crystaldisplay device according to one example of the present invention;

FIG. 15 is a schematic view showing a photo detective liquid crystaldisplay panel according to one example of the present invention;

FIG. 16 is a schematic view showing a photo detective liquid crystaldisplay device according to another example of the present invention;

FIG. 17 is a schematic view showing a photo detective liquid crystaldisplay device according to still another example of the presentinvention;

FIG. 18 is a schematic view showing a photo detective liquid crystaldisplay device and a light pen;

FIG. 19 is a partial cross-sectional perspective view showing a photodetective liquid crystal display device according to one example of thepresent invention;

FIG. 20 is a partially enlarged view showing ‘A’ of FIG. 19;

FIG. 21 is a cross-sectional view taken along the line III-III of FIG.19;

FIG. 22 is a cross-sectional view taken along the line III-III of FIG.19;

FIG. 23 is a cross-sectional view showing pixel regions of the photodetective liquid crystal display device according to one exemplaryembodiment of the present invention; and

FIG. 24 is a cross-sectional view showing photo detective element of thephoto detective liquid crystal display device according to one exemplaryembodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Detailed illustrative embodiments of the present invention are disclosedherein. However, specific structural and functional details disclosedherein are merely representative for purposes of describing exemplaryembodiments of the present invention. This invention may, however, beembodied in many alternate forms and should not be construed as limitedto the embodiments set forth herein.

Accordingly, while the invention is susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention. Like numbers referto like elements throughout the description of the figures.

Embodiment 1 of a Light Pen

FIG. 1 is a schematic view showing a light pen according to a firstexemplary embodiment of the present invention.

Referring to FIG. 1, the light pen 100 includes a body 110, a photodetective module 120, a control module 130, a light generating module140 and a power supply module 150.

The body 110 has a cylindrical shape and has an inner space so as toreceive the photo detective module 120, the control module 130, thelight generating module 140 and the power supply module 150. An opening112 is formed at an end of the body 110, and the light generated fromthe light generating module 140 exits from the opening 112.

The photo detective module 120 is disposed in the body 110. The photodetective module 120 detects image light 10 inputted from an externalsource. The image light 10 is generated from a display device such as aliquid crystal display device. The photo detective module 120 is able todetect white light, monochromatic light and the image light, etc.

The photo detective module 120 outputs a sensing signal in response tothe image light 10. The intensity of the sensing signal outputted fromthe photo detective module 120 is proportional to the intensity of theimage light 10 incident into the photo detective module 120. The sensingsignal is inputted into the control module 130.

The photo detective module 120 is installed in a pocket portion 114having a pocket shape so as to detect the image light 10 that isdirected from an external region of the body 110 to an internal regionof the body 110.

The photo detective module 120 may be a photo sensor such as a photodiode, a photo transistor, or a color sensor that selectively perceivesa light having a frequency corresponding to a red color, a light havinga frequency corresponding to a green color and a third light having afrequency corresponding to a blue color.

The control module 130 is disposed in the body 110 or on the body 110.The control module outputs a control signal in response to the sensingsignal outputted from the photo detective module 120. The control signalturns on or turns off the light generating module 140. The controlmodule 130 determines the level of the control signal based on the levelof the sensing signal outputted from the photo detective module 120. Thecontrol module 130 compares the level of the sensing signal with thelevel of a predetermined reference signal, and outputs the controlsignal when the level of the sensing signal is higher than the level ofthe predetermined reference signal.

The light generating module 140 is disposed in the body 110 or on thebody 110. For example, the light generating module 140 may be installedat another end of the body 110. A driving power signal is applied to thelight generating module 140 in response to the control signal. Forexample, the driving power signal may be supplied from a power supplymodule 150 such as a dry cell battery or mercury battery installed inthe body 110. The driving power signal may be supplied from an externalpower source.

For example, the light generating module 140 may be a light emittingdiode (LED) generating white light similar to sun light. The white lightgenerated from the light generating module 140 is sensing light 142. Thesensing light 142 generated from the light generating module 140 exitsfrom the body 110 through the opening 112.

Hereinafter, the operation of the light pen is illustrated withreference to FIG. 1.

First, when an user moves the light pen 100 toward a surface of adisplay device, on which the photo detective elements are disposed andthe image light 10 is displayed, the image light 10 generated from thedisplay device is detected by the photo detective module 120 of thelight pen 100. The photo detective module 120 outputs the control signalto the control module 130 in response to the image light 10.

The control module generates the control signal in response to thesensing signal outputted from the photo detective module 120. Thedriving power signal is applied to the light generating module 140 inresponse to the control signal. The light generating module 140generates the sensing light 142 directed toward outside of the body 110in response to the driving power signal.

For example, the sensing signal 142 may proceed in reverse direction tothe image light 10. The image light 10 is incident into the light pen100 from outside the light pen 100, and the sensing light 142 exits fromthe light pen 100 toward outside the light pen 100. The sensing light142 generated from the light pen 100 is applied to the photo detectiveelement of the display device.

According to above embodiment of the present invention, since the lightpen 100 detects the light generated from the surface of the displaydevice and generates the sensing light 142, the user need not turn on orturn off the light pen 100, need not apply pressure on the surface ofthe display device so as to use the light pen 100. In addition, sincethe sensing light is generated only when the user brings the light pen100 into contact with the surface of the display device, the powerconsumption may be greatly reduced.

Embodiment 2 of a Light Pen

FIG. 2 is a schematic view showing a light pen according to a secondexemplary embodiment of the present invention. In embodiment 2, allelements except the light generating module denote the same elements inembodiment 1, and will not be further described below to avoid aredundancy.

The light generating module 140 may be comprised of variouscombination(s) of a red light emitting diode (LED) 143, a green LED 144and a blue visible light emitting diode (LED) 145. The red LED generatesred visible light 143 a having the frequency corresponding to a redcolor, the green LED generates green visible light 144 a having thefrequency corresponding to a green color, and the blue LED generatesblue visible light 145 a having the frequency corresponding to a bluecolor.

For example, the light generating module 140 may be comprised of onlyone among the red light emitting diode (LED) 143, the green LED 144 andthe blue light emitting diode (LED) 145. In addition, the lightgenerating module 140 may be comprised of more than two among the redlight emitting diode (LED) 143, the green LED 144 and the blue lightemitting diode (LED) 145.

In this embodiment, the light generating module 140 includes the redlight emitting diode (LED) 143, a green LED 144 and blue light emittingdiode (LED) 145. The red light emitting diode (LED) 143, the green LED144 and the blue light emitting diode (LED) 145 may be respectivelyconnected to the control module 130. Therefore, the control module 130is able to apply driving power signal to the red light emitting diode(LED) 143, the green LED 144 and the blue light emitting diode (LED)145, respectively.

In this embodiment, the red light emitting diode (LED) 143, the greenLED 144 and the blue light emitting diode (LED) 145 are alternately onand off so that red visible light 143 a, green visible light 144 a andblue visible light 145 a are alternately generated.

FIG. 3 is a graph showing driving power pulses generated from a lightemitting module of the light pen of FIG. 2.

Referring to FIGS. 2 and 3, the red, green and blue LEDs 143, 144 and145 alternately are on and off. The control module 130 applies a firstdriving power pulse 132 to the red LED 143 so as to turn on the red LED143 for a time period of a pulse width, so that red visible light 143 ais generated from the red LED 143.

As soon as the red LED 143 is turned off, the control module 130 appliesa second driving power pulse 133 to the green LED 144 so as to turn onthe green LED 144 for a time period of a pulse width, so that greenvisible light 144 a is generated from the green LED 143.

As soon as the green LED 144 is turned off, the control module 130applies a third driving power pulse 134 to the blue LED 145 so as toturn on the blue LED 145 for a time period of a pulse width, so thatblue visible light 145 a is generated from the blue LED 143.

The control module 130 repeats above mentioned processes and alternatelyturns on and off the red, green and blue LEDs 143, 144 and 145 so thered, green and blue LEDs 143, 144 and 145 generate red, green and bluevisible light, respectively.

According to above embodiment, the light pen outputs at least one ofred, green and blue visible light so that the photo detective element ofthe display device may recognizes the light generated from the light peneffectively.

Especially, since the display device such as the liquid crystal displaydevice has color filters, the light pen generates light such as red,green or blue visible light, and the light such as red, green or bluevisible light may pass through the color filters, so that the photodetective element of the display device may recognizes the lightgenerated from the light pen effectively. In addition, the light penalternately outputs red, green and blue visible light, so that the photodetective element of the display device may recognizes the lightgenerated from the light pen effectively under the circumstance wheresun light or indoor lightning are provided.

Embodiment 3 of a Light Pen

FIG. 4 is a schematic view showing a light pen according to a thirdexemplary embodiment of the present invention, and FIG. 5 is a partiallyenlarged view showing ‘A’ of FIG. 4. In embodiment 3, all elementsexcept the light concentrating cover denote the same elements inembodiment 1, and will not be further described below to avoid aredundancy.

Referring to FIG. 4 or FIG. 5, the light concentrating cover 146concentrates the sensing light 142 generated from the light generatingmodule 140 and enhances the brightness of the sensing light 1 42.

The light concentrating cover 146 may have a shape of cup, and isdisposed near the opening 112. The light generating module 140 connectedto the control module 130 is disposed in the light concentrating cover146. The sensing light 142 generated from the light generating module140 is reflected from the light concentrating cover 146, and the sensinglight 142 is concentrated.

A light reflection layer 147 may be further installed inner surface ofthe light concentrating cover 146 so that the light concentrating cover146 may concentrate light effectively. For example, the light reflectionlayer 147 comprises silver (Ag), aluminum (Al) or aluminum alloy.

According to above embodiment, the light generated from the lightgenerating module is concentrated without using lens, so that thebrightness of the sensing light may be enhanced and the photo detectiveelement of the display device may recognizes the sensing lighteffectively.

Embodiment 4 of a Light Pen

FIG. 6 is a schematic view showing a light pen according to a fourthexemplary embodiment of the present invention. In embodiment 4, allelements except a tip and switch denote the same elements in embodiment1, and will not be further described below to avoid a redundancy.

A tip 162 is disposed near the opening 112. The tip 162 has acylindrical flange shape. The tip 162 contacts the surface of thedisplay device, and the light (Hereinafter, referred to as image light)that has image information is generated from the surface of the displaydevice. The sensing light 142 generated from the light generating module140 exits from the tip 162. An elastic member 164 is attached to one endof the tip 162. The tip 162 is compressed backward when the tip 162presses the surface of the display device, and is restored to anoriginal position when the tip 162 is separated from the surface of thedisplay device.

An on/off switch 166 is connected to the tip 162. The switch 166 outputsa switch signal when the tip 162 contacts the surface of the displaydevice and is separated from the surface of the display device. Theswitch signal allows for the control module 130 to provide the lightgenerating module 130 with the driving power signal. The switch 166stops outputting the switch signal to the control module 130 when thetip 162 is restored to the original position. Therefore, the drivingpower signal is no more provided to the light generating module 130.

The control module 130 does not response to the signal generated fromthe switch 166 when the light generating module 140 is turned on or offin response to the sensing signal generated from the photo detectivemodule 120.

According to above embodiment, the light pen has the switch forcontrolling the light generating module by detecting whether the tipcontacts the surface of the display device. Therefore, the light pen mayoperates normally even when the image light exiting from the surface ofthe display device has very low brightness or the image light may notexit from the surface of the display device.

Embodiment 5 of a Light Pen

FIG. 7 is a schematic view showing a light pen according to a fifthexemplary embodiment of the present invention. In embodiment 5, allelements except a light concentrating member denote the same elements inembodiment 1, and will not be further described below to avoid aredundancy.

Referring to FIG. 7, the light concentrating member 170 is disposed nearthe opening 112 of the body 110 so that the sensing light 142 generatedfrom the light generating module 140 may be concentrated onto a smallarea of the surface of the display device. For example, the lightconcentrating member 170 a semi-circular, triangular pyramid orpolypyramid shape. The light concentrating member 170 comprisestransparent resin so that the sensing light 142 may pass through thelight concentrating member 170. The refractivity of the lightconcentrating member 170 is less than that of the air.

The sensing light 142 generated from the light generating module 140exits from the opening 112 and is incident onto the light concentratingmember 170. The sensing light 142 incident onto the light concentratingmember 170 passes through the light concentrating member 170, isrefracted therefrom by the refraction law and exits therefrom. Thesensing light 142 exiting from the light concentrating member 170 isapplied onto a small area of the surface of the display device.

According to above embodiment, since the sensing light exiting from thelight pen is applied onto a small area of the surface of the displaydevice, the brightness of the sensing light is enhanced and the user mayuse the light pen accurately.

Embodiment 6 of a Light Pen

FIG. 8 is a schematic view showing a light pen according to a sixthexemplary embodiment of the present invention. In embodiment 6, allelements except a driving pulse generating module denote the sameelements in embodiment 4, and will not be further described below toavoid a redundancy.

Referring to FIG. 8, the driving pulse generating module 135 isinstalled in the control module 130. The driving pulse generating module135 includes a circuit that converts a DC power signal into a pulsesignal. The driving pulse generating module 135 generates a first pulsehaving a first frequency during a first time period and a second pulsehaving a second frequency during a second time period. The first andsecond pulses are outputted to the light generating module 140.

FIG. 9 is a graph showing first and second driving power pulsesgenerated from a driving pulse generating module of FIG. 8.

Referring to FIGS. 8 and 9, the driving pulse generating module 135outputs the first pulse 132 having the first frequency. The drivingpulse generating module 135 outputs the first pulse 132 for the firsttime period T1. The first pulse 132 has the first cycle period T_(A) anda first pulse width D₁.

The driving pulse generating module 135 outputs the second pulse havingthe second frequency after the first time period T1. The driving pulsegenerating module 135 outputs the second pulse 134 for the second timeperiod T2. The second pulse 134 has the second cycle period T_(B) and asecond pulse width D₂.

The second frequency is longer than the first frequency. Thus, thesecond pulse width D₂ is narrower than the first pulse width D₁. Thesecond cycle period T_(B) is shorter than the first cycle period T_(A).

The driving pulse generating module 135 alternately outputs the firstpulse 132 or the second pulse 134.

The light generating module 140 is disposed inside the body 110 to facethe opening 112. For example, the light generating module 140 includes alight emitting diode that generates light or a semiconductor device thatemits a laser beam in response to the first and second pulses 132 and134. A light concentrating member 145 is further disposed at an end ofthe light generating module 140 from which light is generated andconcentrates the light generated from the light generating module 140 soas to enhance the brightness of the light.

The light generating module 140 is turned on to generate light or turnedoff by the pulses generated from the driving pulse generating module135.

FIG. 10 is a graph showing brightness measured at the light emittingmodule in response to the driving power pulses of FIG. 9.

Referring to FIGS. 9 and 10, the light generating module 140 generates afirst sensing light 142 a for substantially the first time period T1 inresponse to the first pulse 132 generated from the driving pulsegenerating module 135. The first sensing light 142 a flickers withsubstantially the first cycle period. The brightness of the firstsensing light 142 a changes abruptly with substantially the first cycleperiod.

The light generating module 140 generates a second sensing light 142 bfor substantially the second time period T2 in response to the secondpulse 134 generated from the driving pulse generating module 135. Thesecond sensing light 142 b flickers with substantially the second cycleperiod. The brightness of the second sensing light 142 b changesabruptly with substantially the second cycle period. The first andsecond sensing light exit from the tip 162 of the body 110.

According to above embodiment, the light pen generates light havingfrequencies different from that of sun light or indoor lightning, sothat the photo detective element of the display device effectivelyrecognizes the light generated from the light pen.

Embodiment 7 of a Light Pen

FIG. 11 is a graph showing first and second driving power pulsesgenerated from a driving pulse generating module according to a seventhexemplary embodiment of the present invention. In embodiment 7, allelements except the pulses generated from the driving pulse generatingmodule denote the same elements in embodiment 1, and will not be furtherdescribed below to avoid a redundancy.

Referring to FIGS. 8 and 11, the driving pulse generating module 135generates a first pulse 136 having a first frequency and a firstintensity S1 during a first time period T1. The first pulse 136 has thefirst cycle period T_(A) and a first pulse width D₁.

The driving pulse generating module 135 outputs a second pulse 138having the second frequency after the first time period T1. The drivingpulse generating module 135 outputs the second pulse 138 for the secondtime period T2. The second pulse 138 has the second cycle period T_(B),a second intensity S2 larger than the first intensity S1 and a secondpulse width D₂.

The second frequency is longer than the first frequency. Thus, thesecond pulse width D₂ is narrower than the first pulse width D₁. Thesecond cycle period T_(B) is shorter than the first cycle period T_(A).

The driving pulse generating module 135 alternately outputs the firstpulse 136 or the second pulse 138.

FIG. 12 is a graph showing brightness measured at the light emittingmodule in response to the driving power pulses of FIG. 11.

Referring to FIGS. 11 and 12, the light generating module 140 generatesa third sensing light 142 c for substantially the first time period T1in response to the first pulse 132 generated from the driving pulsegenerating module 135. The third sensing light 142 c flickers withsubstantially the first frequency for substantially the first timeperiod T1 and has a first brightness.

The light generating module 140 generates a fourth sensing light 142 dfor substantially the second time period T2 in response to the secondpulse 138 generated from the driving pulse generating module 135. Thefourth sensing light 142 d flickers with substantially the secondfrequency for substantially the second time period T2. The brightness ofthe fourth sensing light 142 d is larger than that of the third sensinglight 142 c.

According to above embodiment, the light pen generates light havingfrequencies and brightness different from those of sun light or indoorlightning, so that the photo detective element of the display deviceeffectively recognizes the light generated from the light pen.

Embodiment 8 of a Light Pen

FIG. 13 is a partial cross-sectional perspective view showing a lightpen according to an eighth exemplary embodiment of the presentinvention.

Referring to FIG. 8, the light pen 100 includes a body 180 and a lightguiding unit 190. The body 180 has a shape of a pen and has an opening183 from which light exit at a first end 185 of the body 180.

The light guiding unit guides the sensing light generated from anexternal source into the body 180 toward the first end of the body 180.For example, the light guiding unit 190 includes an optical cable havingat least one optical fiber.

A light entering part 192 is connected to dummy pixels disposed on anon-effective display region of the liquid crystal display panel. Thesensing light generated from an external source is incident into thelight entering part 192. The light exiting from the dummy pixels isincident into the light guiding unit 190 and exits from a light exitingpart 194. Optionally, the light entering part 192 receives sensing lightgenerated from lightning equipment. The sensing light generated from thelight lightning equipment, as shown in FIG. 6 or FIG. 7, flickers withvarious frequencies.

The light exiting part 194 is extended to the opening 183 of the body180 so as to enhance the brightness of the light supplied to the opticalfiber.

According to above embodiment, the light pen has a simple structure andgenerates light having various frequencies, so that the photo detectiveelement of the display device effectively recognizes the light generatedfrom the light pen.

Embodiment 1 of a Photo Detective Liquid Crystal Display Device

FIG. 14 is a schematic view showing a photo detective liquid crystaldisplay device according to one example of the present invention, andFIG. 15 is a schematic view showing a photo detective liquid crystaldisplay panel according to one example of the present invention.

Referring to FIGS. 14 and 15, the photo detective liquid crystal displaydevice 700 includes a light pen 100, a liquid crystal display panel anda driving module 600.

Since the light pens are already described in the embodiments 1 through8 of the light pen, the light pen 100 will not be further describedbelow to avoid a redundancy. The light pen of this embodiment is one ofthe light pens described in the embodiments 1 through 8 of the lightpen. For example, in the embodiment 1 of the photo detective liquidcrystal display device, the light pen of FIG. 1 is used. Hereinafter, afirst sensing signal is referred to as a signal that is generated by thephoto detective module 120 in responsive to image light 10. The firstsensing signal is different from a second sensing signal generated bythe photo detective element of the liquid crystal display panel 500.

The liquid crystal display panel 500 includes a first substrate 200, asecond substrate 400 facing the first substrate 200, a liquid crystallayer 300, first electrodes 250, a second electrode 450 and photodetective elements 270.

For example, the first and second substrates 200 and 400 comprisetransparent glass. While the first substrate 200 is disposed to face thesecond substrate 400, a sealing member 430 is formed in the peripheralportion of the first and second substrates 200 and 400, and the liquidcrystal layer 300 is interposed between the first and second substrate200 and 400 to be surrounded by the sealing member 430.

The liquid crystal molecules of the liquid crystal layer 300 is arrangedaccording to the electric field applied to the liquid crystal layer 300,so that transmissivity of the light incident into the liquid crystallayer 300 is changed according the alignment angles of the liquidcrystal molecules.

A plurality of first electrodes 250 is disposed on the first substrate200, and the second electrode 450 is disposed on the second substrate400. The first electrode 250 faces the second electrode 450 and theelectric field is applied between the first and second electrodes 250and 450.

For example, when the liquid crystal panel 500 displays a full-colorimage and has 1024*768 resolution, 1024*768*3 first electrodes 250 arearranged in a matrix shape on the first substrate 200.

The first electrode 250 comprises transparent and conductive indium tinoxide (ITO) or indium zinc oxide (IZO).

Referring to FIG. 15, a plurality of thin film transistors (TFTs) 260 iselectrically connected to the first electrodes 250. Pixel voltage isapplied to the first electrodes 250 through the thin film transistors260.

The thin film transistor includes a gate electrode (G), a sourceelectrode (S) and a drain electrode (D).

Hereinafter, a control electrode represents a gate electrode of the thinfilm transistor, a first current electrode represents a source electrode(or a drain electrode) of the thin film transistor, and a second currentelectrode represents a drain electrode (or a source electrode) of thethin film transistor.

The drain electrode is electrically connected to the first electrode250. The gate electrodes are commonly connected to gate lines 285. Thesource electrodes are commonly connected to data lines 280.

The second electrode 450 is formed on an entire surface of the secondsubstrate 400 to face the first electrodes 250. The second electrode 450comprises transparent and conductive indium tin oxide (ITO) or indiumzinc oxide (IZO). Common voltage is applied to the second electrode 450.

Color filters 460 are disposed between the second electrodes 450 and thesecond substrate 400. The color filters 460 are arranged on the secondsubstrate 400 to have substantially the same arrangement as the firstelectrodes 450. Each of the color filters 460 has substantially the samearea as the first electrodes. The color filters 460 include a red colorfilter 462, a green color filter 464 and a blue color filter 466. Thered color filter 462 passes light having wavelength corresponding to redvisible light, the green color filter 464 passes light having wavelengthcorresponding to green visible light, and the blue color filter 466passes light having wavelength corresponding to blue visible light.

The photo detective elements 270 are disposed between the firstelectrodes 250 on the first substrate 200. The photo detective elements270 are arranged in a matrix shape.

Since the configuration and function of the photo detective element 270is disclosed in detail in KR Patent Application No. 2003-12768 (entitled“Liquid crystal display device and method of manufacturing the same”),detailed description will not be shown below. According to the KR PatentApplication No. 2003-12768, the photo detective element includes asensing thin film transistor and a switching thin film transistor. Thesensing thin film transistor receives light generated from externalsource, and the switching thin film transistor receives the output ofthe sensing thin film transistor and generates the second sensing signal(S_(s2)). The photo detective element 270 generates the second sensingsignal (S_(s2)) in response to the light generated from external source,for example, the sensing light 142 generated from the light pen 100. Thesecond sensing signal includes position information, and the positioninformation has a position to which the sensing light 142 is incident.Above mentioned KR Patent Application No. 2003-12768 is incorporatedhereby.

Referring again to FIG. 15, the driving module 600 includes a gatedriver 610, data driver 620, a driving voltage generator 630, a grayscale voltage generator 640, a light source controller 650, a sensedsignal processing unit 660 and a control unit 670.

The driving voltage generator 630 is connected to the gate driver 610,the gray scale voltage generator 640 is connected to the data driver620. The light source controller 650 is connected to a backlightassembly 800 for supplying light to the liquid crystal display panel 500and controls the backlight assembly 800. The sensed signal processingunit 660 processes the second sensing signal generated from the photodetective elements 270.

The gate driver 610 is connected to each of the gate lines 285 andapplies gate driving signal generated from the driving voltage generator630 to each of the gate lines 285. The gate driving signal includes agate turn-on signal (V_(on)), a gate turn-on signal (V_(off)) and acommon voltage signal (V_(com)). The common voltage signal (V_(com)) isapplied to the common electrode of the second substrate 400.

The data driver 620 is connected to each of the data lines 280 andapplies the gray scale voltage generated from the gray scale voltagegenerator 640 to each of the data lines 280.

The control unit 670 controls the gate driver 610, the data driver 620,the driving voltage generator 630, the gray scale voltage generator 640,the light source controller 650 and the sensed signal processing unit660.

The control unit 670 receives video signals from external informationprocessor 900. The video signals includes first red gray scale data(R1), first green gray scale data (G1), first blue gray scale data (B1),a vertical synchronizing signal (V_(sync)) a horizontal synchronizingsignal (H_(sync)) a main clock signal (CLK) and data enable signal (DE),etc.

The control unit 670 converts the first red, green and blue gray scaledata (R1, G1, B1) into second red, green and blue gray scale data (R2,G2, B2), respectively, SO that the second red, green and blue gray scaledata (R2, G2, B2) are used by the liquid crystal display panel.

The control unit 670 outputs the second red, green and blue gray scaledata (R2, G2, B2) and data control signal to the data driver 620. Thedata control signal includes a horizontal synchronization start signal,a load signal and a data clock signal, etc. The second red, green andblue gray scale data (R2, G2, B2) are inputted to the first, second, . .. , last data lines in response to the horizontal synchronization startsignal. Analogue gray scale data is applied to the data lines 280 inresponse to the load signal.

In addition, the control unit 670 outputs a gate control signal to thegate driver 610. The gate control signal includes a verticalsynchronization start signal (STV), a gate clock signal (CPV) and a gateon enable signal (OE). A gate turn-on pulse is applied to the gate linesin response to the vertical synchronization start signal (STV). The gateline is selected when the gate turn-on pulse is applied to the gateline. The gate clock signal (CPV) controls the gate turn-on pulse to beoutputted to the gate lines. The pulse width of the gate turn-on pulseis controlled by the gate on enable signal (OE), so that the gateturn-on pulse is sequentially applied to adjacent gate lines. The gateclock signal (CPV) and the gate on enable signal (OE) are supplied tothe driving voltage generator 630.

The data driver 620 receives analog gray scale voltage from the grayscale voltage generator 640, and outputs the analog gray scale voltageto the data lines 280 in response to the data control signal. The analoggray scale voltage corresponds to the bit value of the second red, greenand blue gray scale data (R2, G2, B2). The gate driver 610 applies thegate turn-on pulse to the first gate line 285 in response to the gatecontrol signal from the control unit 670, so that the thin filmtransistors connected to the first gate line are turned on.

The analog gray scale voltage is applied to the first electrode 250through the drain electrode of the thin film transistors to which thegate turn-on pulse is applied. The control unit 670 performs aboveprocedure for one frame time, for example, about 16.6 ms. For example,the control unit 670 displays 30 frames of images per a second so at todisplay letters, images and moving pictures.

After one frame time, the analog gray scale voltage is applied to thefirst electrodes on the first substrate 200, the common voltage isapplied to the second electrode 450 on the second substrate 400, and theliquid crystal molecules of the liquid crystal 300 are arrangedaccording to the electric field difference between the first and secondelectrodes.

The backlight assembly 800 faces the first substrate 200, and generateslight that sequentially passes through the first substrate 200, theliquid crystal layer 300 and the second substrate 400. The light passedthrough the liquid crystal layer 300 is image light 10, and the imagelight 10 is incident into eyes of the user through the second substrate400.

When the user works with the light pen 100, the sensing light 142 isapplied to the photo detective element 270 disposed between the firstelectrodes. The light generating module 140 of the light pen 100generates the sensing light 142 when the photo detective module 120detects the image light 10.

When the sensing light 142 generated from the light pen 100 is incidentinto the photo detective elements 270, a second sensing signal isgenerated from the photo detective elements into which the sensing light142 is incident. The second sensing signal has position informationrepresenting a position to which the sensing light is incident. Thesensed signal processing unit 660 transforms the second sensing signalinto a digital signal to output position data to the control unit 670.

The control unit 670 receives the position data and output the positiondata

The sensed signal processing unit 660 outputs the position data to theinformation processor 900. The information processor 900 receives theposition data to output new video signals (new RGB signals, etc.) to thecontrol unit 670.

Although the information processor 900 is externally connected to thecontrol unit 670 in FIG. 15, the information processor could also beincluded in the control unit 670. In other words, the control unit 670may performs the function of the information processor 900.

Embodiment 2 of a Photo Detective Liquid Crystal Display Device

FIG. 16 is a schematic view showing a photo detective liquid crystaldisplay device according to another example of the present invention. Inembodiment 2, all descriptions except a method of supplying drivingpower signal to the light pen are the same as embodiment 1, and will notbe further described below to avoid a redundancy.

Referring to FIG. 16, the light source controller 650 of the drivingmodule 600 outputs driving power signal to the light pen 100 throughline 655. The line 655 is connected to the control module 130 of thelight pen 100, and the control module 130 applies the driving powersignal to the light generating module 140.

According to above embodiment, the driving power signal for driving thelight pen is coupled with periodic turn-on or turn-off cycle of thelight source controller 650 of the driving module 600, so that thenumber of parts used in the light pen may decrease. In addition, theweight and size of the light pen may be reduced since the light pen doesnot have the battery or mercury cell for supplying the driving powersignal to the light pen.

Embodiment 3 of a Photo Detective Liquid Crystal Display Device

FIG. 17 is a schematic view showing a photo detective liquid crystaldisplay device according to still another example of the presentinvention, and FIG. 18 is a schematic view showing a photo detectiveliquid crystal display device and a light pen. In embodiment 3, allelements except the comparator module installed in the sensed signalprocessing unit denote the same elements in embodiment 1, and will notbe further described below to avoid a redundancy.

Referring to FIGS. 17 and 18, the sensed signal processing unit 660receives the second sensing signal outputted from the photo detectiveelement 220.

The sensed signal processing unit 660 further includes the comparatormodule 665.

The photo detective element 270 is sensitive to light. When the userworks with the light pen under an external light such as the sun lightor an indoor lightning, the external light is incident into the entiresurface of the liquid crystal display panel 500. The photo detectiveelements 270 outputs an analog sensing signal based on brightness andintensity of illumination of the external light applied to the photodetective elements 270. The analog sensing signal due to the externallight may be recognized as the sensing signal generated from the lightpen, so that undesired images may be displayed on the liquid crystaldisplay panel. Above abnormal operation of the liquid crystal displaydevice may be shown especially under the sun light because the sun lighthas strong intensity.

The comparator module 665 compares the intensity and frequency of thesensing signal with those of predetermined reference signals so as todistinguish the external light from the sensing signal generated fromthe light pen. The abnormal operation of the liquid crystal displaydevice may be reduced by the comparator module 665.

The sensed signal processing unit 660 presets reference light as thesensing signal generated from the light pen. For example, the referencelight has a first frequency for a first time period and a secondfrequency for a second time period.

The first and second time period is short enough so that the user maywrite letters or draw figures while the user moves the light pen.

Since the light pen has the same configuration as that of embodiment 6or 7, the light pen will not be described below to avoid a redundancy.

Hereinafter, the operation of the photo detective liquid crystal displaydevice is described.

First, the user presses the light pen 100 to be closely adhered to thesurface of the liquid crystal display panel, and the sensing light isgenerated from the light pen 100. The light pen generates a firstsensing light having the first frequency for the first time period and asecond sensing light having the second frequency for the second timeperiod. The first frequency is different from the first frequency. Thefirst time period is the same as the second time period, or may bedifferent from the second time period. The first and second frequencieshave a frequency except a commercial power frequency such as about 50 Hzor about 60 Hz.

The first and second sensing lights generated from the light pen 100 isapplied to the photo detective elements 270 arranged in a matrix shapeon the liquid crystal display panel, and the photo detective element 270outputs an analog signal corresponding to the frequency of the sensingsignal to the sensed signal processing unit 660.

The comparator module 665 compares the sensing signal outputted from thephoto detective elements 270 with the predetermined reference signals,divides the analog signal generated due to the sensing light outputtedfrom the light pen 100, converts the analog signal into digital signal,and outputs the digital signal to the control unit 670.

The control unit 670 outputs the digital signal to the informationprocessor 900.

The information processor 900 processes the digital signal and outputsnew video signals to the control unit 670, so that images are displayedon the liquid crystal display panel.

Embodiment 4 of a Photo Detective Liquid Crystal Display Device

FIG. 19 is a partial cross-sectional perspective view showing a photodetective liquid crystal display device according to one example of thepresent invention, FIG. 20 is a partially enlarged view showing ‘A’ ofFIG. 19, and FIG. 21 is a cross-sectional view taken along the lineIII-III of FIG. 19.

Referring to FIGS. 19, 20 and 21, the liquid crystal display panel 1400includes a first substrate 1100, a second substrate 1200 facing thefirst substrate 1100, and a liquid crystal layer 1300.

The first substrate 1100 includes a first transparent substrate 1110, adriving voltage applying element 1120, color filters 1130 (refer to FIG.22), a photo detective part 1140, pixel electrodes 1150 and a blackmatrix pattern (or light shielding pattern) 1160.

The first transparent substrate 1110 is a glass substrate having a highlight transmissivity, and has a plurality of pixels 1101 (refer to FIG.20). A pixel 1101 is a unit for displaying an image. Hereinafter, apixel region is referred to as the region in which a plurality of pixelsis formed. For example, when the liquid crystal panel has 1024*768resolution, 1024*768*3 pixels are formed on the first transparentsubstrate 200. The user recognizes images through the light passingthrough the pixels 1101.

The driving voltage applying element 1120 includes gate lines 1122, datalines 1124 and first thin film transistors 1123.

The gate lines 1122 are extended in a first direction on the firsttransparent substrate 1110 to inside pixel 1101. The data lines 1124 areextended in a second direction substantially perpendicular to the firstdirection on the first transparent substrate 1110 to be formed betweenpixels 1101.

For example, when the liquid crystal device 1400 has 1024*768resolution, 768 gate lines are formed on the first transparent substrate1100, and 1024*3 data lines are formed on the first transparentsubstrate 1100.

The first thin film transistor 1123 is formed in each of the pixels 1101on the first transparent substrate 1110. The first thin film transistor1123 is disposed at the point where the gate line 1122 crosses the dataline 1124. The first thin film transistor 1123 includes a gate electrode(G), a channel (C), a source electrode (S) and a drain electrode (D).The gate electrode (G) is extended from the gate line 1122 in the seconddirection to the pixel 1101. The channel (C) is disposed over the gateelectrode (G) and is insulated from the gate electrode (G). The channel(C) comprises amorphous silicon film and n⁺ amorphous silicon filmdisposed on the amorphous silicon film. The n⁺ amorphous silicon filmhas a first part and a second part. The source electrode (S) is extendedfrom each of the data lines 1124 to the pixel 1101. The source electrode(S) contacts with the first (or second) part of the n⁺ amorphous siliconfilm, and the drain electrode (D) contacts with the second (or first)part of the n⁺ amorphous silicon film.

FIG. 22 is a cross-sectional view taken along the line III-III of FIG.19 so as to show the portion where the photo detective elements areformed.

Referring to FIGS. 20 and 22, the photo detective part 1140 includes afirst sensing line 1142, a second sensing line 1144 and photo detectiveelements 1146 and 1148.

The first sensing line 1142 is formed inside the pixel 1101 along thesecond direction on the first transparent substrate 1110. The firstsensing line 1142 is formed as the same layer as the data line 1124, andis spaced apart from the data line 1124 by a predetermined distance tobe electrically insulated from the data line.

The second sensing line 1144 is formed between the pixels 1101 along thefirst direction on the first transparent substrate 1110. The secondsensing line 1144 is formed as the same layer as the gate line 1122, andis spaced apart from the gate line 1122 by a predetermined distance tobe electrically insulated from the gate line 1122.

For example, the photo detective elements 1146 and 1148 are formed inselected pixels of all pixels 1101. The photo detective elements 1146and 1148 output the signal having position information to the firstsensing line 1142 in response to the external light applied from outsidethe liquid crystal display device 1400. The photo detective elements1146 and 1148 include a second thin film transistor 1146 and a thirdthin film transistor 1148.

The second thin film transistor 1146 is turned on in response to theexternal light. The second thin film transistor 1146 includes a gateelectrode (G), a channel (C), a source electrode (S) and a drainelectrode (D).

The gate electrode (G) is extended from the second sensing line 1144 inthe second direction to each of the pixels 1101. The channel (C) isdisposed over the gate electrode (G) and is insulated from the gateelectrode (G). The channel (C) comprises amorphous silicon film and n⁺amorphous silicon film disposed on the amorphous silicon film. The n⁺amorphous silicon film has a first part and a second part. The amorphoussilicon film and the n⁺ amorphous silicon film transforms the externallight into electric current (or energy) to allow the second thin filmtransistor to be electrically conducted. The source electrode (S) isextended from the data lines 1124 to the pixel 1101. The sourceelectrode (S) contacts with the first (or second) part of the n⁺amorphous silicon film, and the drain electrode (D) contacts with thesecond (or first) part of the n⁺ amorphous silicon film. The drainelectrode (D) is extended in the direction along which the third thinfilm transistor 1148 is formed.

The third thin film transistor 1146 includes a gate electrode (G), achannel (C), a source electrode (S) and a drain electrode (D).

The gate electrode (G) is extended from the gate line 1122 in the seconddirection to each of the pixels 1101. The channel (C) is disposed overthe gate electrode (G) and is insulated from the gate electrode (G). Forexample, the channel (C) comprises amorphous silicon film and n⁺amorphous silicon film disposed on the amorphous silicon film. The n⁺amorphous silicon film has a first part and a second part. The sourceelectrode (S) contacts with the first (or second) part of the n⁺amorphous silicon film, and the drain electrode (D) contacts with thesecond (or first) part of the n⁺ amorphous silicon film. The drainelectrode (D) is extended from the first sensing line 1142 along thefirst direction to the pixel 1101.

The channel (C) formed on the second thin film transistor 1146recognizes the red visible light most sensitively. Therefore, the photodetective elements 1146 and 1148 are formed in selected pixels among thepixels on which the red color filters 1132 are formed so that the photodetective elements 1146 and 1148 may effectively recognize the externallight.

Referring to FIGS. 20, 21 and 22, the red, green or blue color filter1130 is disposed in each of the pixels 1101. Edges of the red, green andblue color filters overlap each other so as to shield the light leakingbetween the pixels. Therefore, the black matrix pattern is notnecessarily required so as to shield the light leaking between thepixels.

The color filters 1130 include a red color filter 1132, a green colorfilter 1134 and a blue color filter 1136. The red color filter 1132passes light having wavelength corresponding to the red visible light,the green color filter 1134 passes light having wavelength correspondingto the green visible light, and the blue color filter 1136 passes lighthaving wavelength corresponding to the blue visible light.

For example, n(n is natural number)th pixel includes the red colorfilter 1132, (n+1)th pixel includes the green color filter 1134, and(n+2)th pixel includes the blue color filter 1136. The color filters1130 cover the entire surface of the pixels 1101. Each of the colorfilters 1130 includes contact holes 1132 a, 1134 a and 1136 a, and thecontact holes 1132 a, 1134 a and 1136 a are formed over the drainelectrode (D) of the thin film transistor 1120.

The pixel electrodes 1150 are formed in the pixel region and aredisposed over the color filters 1130. The pixel electrodes 1150 compriseITO or IZO. The pixel electrodes 1150 are electrically connected to thedrain electrode (D) of the thin film transistor 1120 through the contactholes 1132 a, 1134 a and 1136 a formed on the color filters 1130. Thepixel electrodes 1150 receives the driving power signal from the firstthin film transistor 1120.

The black matrix pattern 1160 is formed on the pixel electrodes 1150.The black matrix pattern 1160 is electrically connected to the drainelectrode (D) of the first thin film transistor 1123 through the contactholes 1132 a, 1134 a and 1136 a formed on the color filters 1130. Theblack matrix pattern 1160 comprises aluminum neodymium (Al—Nd) havinghigh reflectivity. The black matrix 1160 covers the driving voltagegenerator 1120, the first sensing line 1142, the second sensing line1144 and the third thin film transistor 1148. The black matrix 1160shields the light leaking between the first and the second substrates1100 and 1200, and prevents the first and third thin film transistors1123 and 1148 from being exposed to the external light. In addition, theblack matrix pattern 1160 has openings that is disposed over the secondthin film transistor 1146, and passes the light incident into the pixels1101 through the opening, so that the light supplied from the light penmay be applied to the second thin film transistor 1146.

Referring to FIGS. 21 and 22, the second substrate 1200 further includesa second transparent substrate 1210 and a common electrode 1220. Thecommon electrode 1220 is formed on entire surface of the secondtransparent substrate 1210 and comprises ITO or IZO.

The first and second substrates 1100 and 1200 are combined with eachother so that the pixel electrodes 1150 face the common electrode 1220.A sealing member 1115 (refer to FIG. 19) is formed in the peripheralportion of the first and second substrates 200 and 400 to have a bandshape so as to combine the first and second substrates 1100 and 1200.

The liquid crystal layer 1300 is interposed between the first and secondsubstrate 1100 and 1200. The liquid crystal molecules of the liquidcrystal layer 1300 is arranged according to the electric field formedbetween the pixel electrodes 1150 and the common electrode 1220.

According to above embodiment, the driving voltage generator 1120, thecolor filters 1130, the photo detective part 1140, the pixel electrodes1150 and the black matrix pattern (or light shielding pattern) 1160 areformed on the first substrate 1100, and only the common electrode 1220is formed the second substrate 1200. Therefore, the first and secondsubstrates 1100 and 1200 are easily assembled each other and thereliability of the liquid crystal display device is enhanced because themis-align between the first and second substrates 1100 and 1200 isreduced. In addition, since the distance between the gate lines 1122,data lines 1124 and the pixel electrodes 1150 increases due to the colorfilters 1130 formed on the pixels 1101, and the area of the openingincreases. Therefore, the resolution of the display device is enhancedcompared with the conventional display device using the touch panel.

In addition, the photo detective part 1140 for providing positioninformation is formed in the liquid crystal display device 1400, so thatthe liquid crystal display device has enhanced optical properties,thinner thickness and reduced manufacturing cost compared with theconventional display device using the touch panel. In addition, thephoto detective part 1140 is formed only on the pixels 1101 in which thered color filters 1132 are formed, so that the photo detective part ofthe display device may recognizes the light generated from the light peneffectively.

Embodiment 5 of a Photo Detective Liquid Crystal Display Device

FIG. 23 is a cross-sectional view showing pixel region of the photodetective liquid crystal display device according to one exemplaryembodiment of the present invention, and FIG. 24 is a cross-sectionalview showing photo detective element of the photo detective liquidcrystal display device according to one exemplary embodiment of thepresent invention. In embodiment 5, all descriptions except that theblack matrix pattern is formed on the second substrate are the same asembodiment 4, and will not be further described below to avoid aredundancy.

Referring to FIGS. 23 and 24, the second substrate 1200 further includesa black matrix pattern 1230. For example, the black matrix pattern 1230is formed on the common electrode 1220 in a matrix shape.

The black matrix pattern 1230 is formed by patterning black matrix thinfilm comprising organic material that has light transmittance or lightshielding ratio similar to chromium (Cr). In other words, the blackmatrix thin film transmits light and shields light in the similar degree(or ratio) to the chromium (Cr). Particularly, the black matrix pattern1230 comprises black organic material that has light transmittance orlight shielding ratio similar to chromium (Cr).

The black matrix 1230 covers the driving voltage generator 1120, thefirst sensing line 1142, the second sensing line 1144 and the third thinfilm transistor 1148. The black matrix 1230 shields the light that leaksbetween the first and the second substrates 1100 and 1200 through thedriving voltage generator 1120, the first and second sensing line 1142and 1144 and the third thin film transistor 1148. The black matrix 1230prevents the first and third thin film transistors 1123 and 1148 frombeing exposed to the external light. In addition, the black matrixpattern 1160 has openings 1230 a that are disposed over the second thinfilm transistor 1146, and passes the light incident into the pixels 1101through the openings 1230 a, so that the light supplied from the lightpen may be applied to the second thin film transistor 1146.

The black matrix pattern 1230 passes the light incident into the pixels1101 through the opening 1230 a, and shields the light passing betweenthe pixels 1101.

The black matrix pattern 1230 completely shields the light passing theoverlapped color filters 1130, so that the display quality is enhanced.

For example, a twisted nematic liquid crystal (TN LC) or a verticalalignment mode liquid crystal (VA LC) is disposed between the firstsubstrate 1100 and the second substrate 1200 on which the black matrixpattern 1230 is formed.

According to above embodiment, the black matrix pattern is formed on thecommon electrode of the second substrate, so that the light passingbetween the pixels is completely shielded and the display quality isenhanced.

Although above preferred embodiments discuss the liquid crystal displaydevice, the organic electroluminescence device could be utilized.

According to the present invention, the light pen detects image lightgenerated from the surface of the display device, and generates sensinglight by means of the light source mounted in the light pen. Therefore,the power consumption of the light pen is greatly reduced, and thebrightness of the sensing light is greatly enhanced. The light pengenerates light different from the external light such as sun light,etc., and the display device recognizes the light generated from thelight pen effectively. Therefore, the display device may operate withoutfailure.

Having described the exemplary embodiments of the present invention andits advantages, it is noted that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by appended claims.

1. A liquid crystal display device comprising: a light pen including: abody; a photo detective module that is configured to detect a firstlight inputted from an external source to output a first sensing signal,the photo detective module being disposed in the body; a control modulethat is configured to output a control signal in response to the firstsensing signal; and a light generating module that is configured toreceive a driving power signal in response to the control signal togenerate a second light; a liquid crystal display panel including: afirst substrate; a second substrate facing the first substrate; a liquidcrystal layer interposed between the first substrate and the secondsubstrate; a plurality of first electrodes disposed on the firstsubstrate; a second electrode disposed on the second substrate; and aphoto detective element that is configured to detect the second light tooutput a second sensing signal having a position information, the photodetective element being disposed between the first electrodes, theposition information having a position to which the second light isincident; and a driving module that is configured to generate first andsecond driving signals, the first driving signal being applied to thefirst and second electrodes so that the liquid crystal display paneloutputs the first light, and the second driving signal being applied tothe first and second electrodes in response to the second sensing signalso that the liquid crystal display panel outputs a third light.
 2. Theliquid crystal display device of claim 1, wherein the liquid crystaldisplay device further includes a lamp assembly having a lamp and aninverter, the lamp and the inverter face the first substrate, theinverter supplies a power signal to the lamp, and the driving powersignal is supplied by the inverter.
 3. A liquid crystal display devicecomprising: a light pen including: a body; a driving pulse generatingmodule that is configured to generate a first driving power pulse havinga first frequency during a first time period and a second driving powerpulse having a second frequency during a second time period, the drivingpulse generating module being disposed in the body; and a lightgenerating module that is configured to generate a first light inresponse to the first driving power pulse and a second light in responseto the second driving power pulse, the first light flickering at a thirdfrequency, and the second light flickering at a fourth frequency; aliquid crystal display panel including: a plurality of pixels that isconfigured to control a transmissivity of a third light passing througha liquid crystal layer to display an image; and a photo detectiveelement that is configured to detect a position into which the first andsecond lights are incident, the photo detective element being disposedbetween the pixels; a sensed signal processing unit including acomparator module, the comparator module comparing a first intensity ofa first sensing signal with a second intensity of a second sensingsignal, the first sensing signal corresponding to a third light inputtedfrom an external source, the second sensing signal corresponding to thefirst and second lights; and a driving module that is configured togenerate first and second driving signals, the first driving signalbeing applied to the pixels, and the second driving signal being appliedto the pixels in response to the second sensing signal.
 4. A displaydevice comprising: a light pen including: a body; a photo detectivemodule that is configured to detect a first light inputted from anexternal source to output a first sensing signal, the photo detectivemodule being disposed in the body; a control module that is configuredto output a control signal in response to the first sensing signal; anda light generating module that is configured to receive a driving powersignal in response to the control signal to generate a second light; adisplay unit including a plurality of photo detective elements, thephoto detective elements outputting the first light, detecting thesecond light to output a second sensing signal having a positioninformation, the position information having a position to which thesecond light is incident; a driving module that is configured togenerate first and second driving signals, the first driving signalallowing the display unit to output the first light, and the seconddriving signal allowing the display unit to output a third light inresponse to the second sensing signal.